Built-in self-cleaning wall oven

ABSTRACT

A built-in, self-cleaning wall oven construction for a hightemperature self-cleaning oven cavity in which airflow passages are provided around the oven cavity in a manner that convection airflow alone is adequate to limit the maximum external temperatures sufficiently to meet the established temperature limits.

United States Patent 56] References Cited UNITED STATES PATENTS [72] Inventors Eugene J. Barnett;

Gerald E. Baker,

both of Mansfield, Ohio 126/21 126/21 A 126/21 A 126/21 A AX 33 77 22 66 22 ll U mm n mmm m smmmmn e tao r. 0!. .l a PQ H h ac PHSSRG 844789 566666 999999 HHHHHH 629352 485679 455462 9 0045 325 88 233333 n 0 a m n. r o C c .1 r w l a 2e oh h8 ly ,lnu 1 mm nn t 6 uh SJJWP 0 de N ee d P mms AFPA 11:1] 253 2247 [[[1 Primary Examiner-Charles .l. Myhre Attorneys F. H. Henson and E. C. Arenz n, se1fcleaning wall oven construction mperature self-cleanin n b A n C M T s B A for a high-te g oven cavity in which airflow passages are provided around the oven cavity in a manner [52] US. 126/21 R, 126/273A t 8 mm .H .mo 1... y CH... n r @cl aw S 1% m. lm m am e W m Om fl .U m a 6 ID. n 0mm nr Ce end v e n h 0 .W m u a t mma 2.1...A B 3 5 7 19 C 4W 22 F12 9 3 9 m3 NA .l m2

..S 1 m d Ld .m 1.1 0 55 [l PATENTEDJANI 1 m2 3l633l561 sum 1 OF 2 WITNESSES INVENTORS Eugene J. Burnett Gerald E. Baker ATTORNEY PATENTEU JAN} 1 1912 SHEEI 2 BF 2 BACKGROUND OF THE INVENTION 1. Field of the Invention The invention pertains to the art of domestic self-cleaning wall oven constructions.

2. Description of the Prior Art US. Pat. No. 3,310,046 is an example of one self-cleaning wall oven construction in which provision is made for accomplishing generally the same objects that our invention contemplates accomplishing. That patent is related to a self-cleaning oven of a character having a marketed version which is believed to operate with a cycling temperature during a cleaning operation of about 880 F. In contrast therewith, the version of self-cleaning oven with which our invention is concerned at this time, has a cycling temperature of about l,000 F. or somewhat higher. It is interesting in this connection that the oven structure shown in the patent is taught as including airflow inducing means (i.e., blower means) to ensure circulation of air in passages formed around most sides of the oven cavity and then direct the air over a vent duct which carries oven gases from the catalytic oxidation unit to the room in which the oven is situated.

In an oven construction according to our invention adequate airflow about the insulated oven cavity is attained to limit the external cabinet temperatures to the established values without the use of airflow inducing means, even though the oven cavity operates at a substantially higher temperature than in the noted patent.

A construction according to our invention is also compatible with the apparatus and method of self-cleaning taught in US. Kastovich application Ser. No. 552,663, now U.S. Pat. No. 3,504,161, and with the control systems and oven door latch and lock arrangements disclosed in US. Pat. Nos. 3,387,874, 3,390,909, and 3,410,988.

SUMMARY OF THE INVENTION A built-in, self-cleaning wall oven according to the invention includes an insulated oven liner forming an oven cavity having an open front adapted to be closed by a door, air passages formed by panels spaced outwardly from the insulated liner along at least the top, rear and opposite sides of the cavity, the passages all being in open communication with each other, an air inlet across substantially the entire front width of the oven and below the oven to admit room air to the passages, a control and wiring chamber overlying the top air passage and having a control panel forming the front wall of the chamber, this control chamber being thermally and airflow isolated from the passages, an air outlet opening for the passages at the front of the top air passage, the air outlet opening being located between the control panel and the top of the door, an oven gas vent duct having an inlet communicating with the oven cavity and extending for at least half the depth of the oven in the top air passage to place the duct in open heat transfer relation with the air passing through the top air passage, the duct having a discharge opening between the top of the door and the control panel, and with the airflow passages being devoid of airflow inducing means so that the airflow through the passages is created by convection currents. In the currently preferred version of the invention, the bottom wall of the top air passage is formed by a metallic panel overlying the thennal insulation on the top of the oven cavity and the vent duct is secured to the metallic panel in a relatively good heat conducting relation to promote the transfer of heat from the exhaust duct to the metallic panel so that the flow over the entire area of the panel aids in picking up heat from the exhaust duct.

Additional features of the invention will be noted in the following description.

DRAWING DESCRIPTION FIG. 1 is a partly broken and partly schematic isometric view of a built-in, self-cleaning oven incorporating the inven- LII tion, this view being intended to serve as an aid in understanding the overall airflow system; and

FIG. 2 is a right side elevational view, partly broken and partly in section, and also showing the relative location of the front wall ofa cabinet in which the oven is installed.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1 and 2, the oven cavity 10 is generally defined by a box-shaped oven liner 12 provided with an open front 14 adapted to be closed by the insulated front door 16, all five sides of the oven liner are surrounded by thermal insulation l8 as is conventional in the pyrolytic type self-cleaning ovens.

Wall means spaced outwardly from the insulated oven cavity are provided along at least the top, rear, and opposite sidewalls to define airflow passages which are in open communication with each other. In the currently preferred embodiment the inner faces of the air passages are defined by metal panels which also serve to hold the blankets of thermal insulation 18 in place. In FIGS. 1 and 2 the side inner wall panel is designated 20, the top inner wall panel 22, the rear inner wall panel 24, the side outer wall panel 26, the top outer wall panel 28, and the rear outer wall panel 30. The side air passage is designated 32, the top air passage 34, and the rear air passage 36. The side opposite from that shown in FIGS. 1 and 2, is a mirror image from a constructional standpoint and accordingly provides a side air passage identical to the side air passage 32.

The paths that the airflow follows is indicated by the arrows in FIGS. 1 and 2. The oven as a whole is so set in a rectangular opening the cabinet 38 (FIG. 2) that a gap forming an air inlet 40 is defined across substantially the entire front width of the oven below the door to admit room air to the space below the oven. A relatively shallow bottom channel 42 which is open at the front and the rear ends thereof and has a width nearly as great as the width of the oven isolates the bottom inner panel 44 from wood cabinet structure therebelow and also insures the provision of an air passage for air to pass below the exterior face of the panel 44. The air which enters through the gap 40 flows along the entire width of the bottom, part of it through the channel and part of it around the channel 42. Some of this air passes to the side and upwardly through the opposite side spaces 32, while the remainder of it passes to the rear and up through a gap 46 defined between an inclined flange 48 at the lower end of the rear inner panel 24, and the bottom flange 50 at the lower edge of the rear outer panel 30. The slots 52 at the sides of the front peripheral frame serve as thermal breaks for conducted heat and also admit a limited amount of air to the side air passages 32.

The air which flows upwardly through both side air passages 32, and up through the rear passage 36 joins in the top air passage 34 and flows forwardly to exit out of an air outlet opening 54 at the forward end of the top air passage. An openwork grill 56 is provided at the opening. Thus, the air flow system as a whole is designed that room air will be admitted below the oven and flow along the bottom to the sides and the rear, and then upwardly along these opposite side and rear passages, and then forwardly through the top air passage to the outlet opening at the front. While the bottom channel 42 is desirable for the single wall oven, where a double-oven of the type having a self-cleaning wall oven mounted on top of an ordinary cooking oven is involved, the bottom channel 42 is obviously not necessary. However, in such a case, the airgap 40 is still provided at the bottom front edge of the lower oven and the air flows upwardly along the sides and rear of the bottom non-self-cleaning oven in less-confined paths and then flows through the already described passages of the upper selfcleaning oven.

The oven cavity 10 includes the usual heating elements such as the heating element 58 at the top of the oven cavity. In accordance with the method of cleaning and smoke elimination taught in the noted Kastovich patent application, the element is mounted immediately below a plenum structure 60 provided with apertures therein in the same array as the array of the element so that the gases produced during a cleaning cycle are constrained to pass closely by the element and into the plenum in leaving the oven cavity during a heat cleaning cycle.

The gases are then directed through a vertical conduit 62 which extends through the insulation located between the upper wall of the inner liner and the lower wall 22 of the top air passage. The conduit 62 is located more closely to the rear of the oven than to the front so that the vent duct 64 which receives the gases from the conduit 62 carries them a substantial distance to the forward end and outlet 66 of the vent duct. The duct may take the general form of a downwardly open channel having edge flanges 68 secured directly, as by spot welding, to the face of the top inner panel 22 so that the duct is in excellent heat conducting relation with the inner panel 22. By locating the conduit 62 near the rear portion of the oven, a relatively long vent duct is required. This is advantageous since the inner panel 22, to which the duct is secured in good heat conducting relation, forms the bottom of the top air passage 34 and there is provided a substantial surface area of duct in open heat transfer relation with the air passing through the top air passage. Also, the long vent duct path results in the hottest part of the duct being located at a point where the convection airflow passing thereover is cooler than if the duct started near the front part of the oven. It will also be appreciated that by placing the vent duct in good heat conducting relation with the inner panel 22, heat is conducted from the exhaust duct out over an extended surface area of the panel 22 for being swept by the air passing forwardly through the top air passage 34.

Since the version of the wall oven in which our invention is incorporated, is of the character operated in accordance with the noted Kastovich application, the temperature of the air exiting from the oven cavity during a cycling portion of the heat cleaning operation is in the order of about 1,000 to L050 F. The temperature of this gas is reduced substantially by the time it is exhausted from the opening 66 at the forward end of the vent duct 64 by virtue of the relatively cooler convection air passing over the duct so as to cool the vent gases passing through the duct.

A control and wiring chamber 70 is provided in overlying relation to the top air passage 34. The forward face of the chamber is provided with a control panel 72 for carrying the usual control knobs, clocks and the like typically provided with such ovens. The open-work grill 56 serving as the vent trim is made as a separate piece from the control panel frame 74 so that they may be mounted in spaced-apart relation with an airgap therebetwe en to prevent conductive heat flow between the separate pieces. This also permits the vent trim 56 to be separately moved for making adjustments on forward portions of the latch-lock arrangement which are located near the forward end of the top air passage 34.

To thermally isolate the control and wiring chamber 70 from the top air passage 34, a separate blanket of thermal insulation such as fiber glass 76 is placed upon the outer face of the top outer panel 28. It will be noted from FIG. 2 that the top outer panel 28 has a rear edge 78 which terminates short of the rearmost wall 30 so that a gap 80 is provided therebetween. The blanket of fiber glass or comparable thermal insulation 76 extends rearwardly to the rear wall 30 to provide a flexible type of seal through which the bundles of control wires 82 can pass. The control wires 82 of course connect the various operable controls at the front panel 72 with other electrical components located in the rear air passage 36.

The top wall of the control and wiring chamber 70 is formed by a top panel 84. This panel and the rear outer wall 30 are, in the currently preferred version of an oven incorporating our invention, of a high emissivity such as so-called black beauty steel, for the purpose of absorbing and radiating heat to a greater degree than the heat is reflected. In contrast therewith, the inner wall panels 20, 22 and 24, forming the inner walls of the air passages are of aluminum-coated steel, and the outer sidewalls 26 are of galvanized steel. The aluminum-coated steel and galvanized steel of course provide a substantially greater degree of reflectivity of heat than the dark-colored panels 84 and 30 at the top and rear of the oven. The reasons for using panels of different heat reflectivity may be understood better from the following. The top wall 84 and the rear wall 30 are spaced a substantially greater distance from the oven cavity than the other panels and accordingly are typically cooler than the panels forming the sidewalls of the side passages which latter passages are relatively narrow. Thus the darker top panel 84 and the rear panel 30 (with high emissivity) may be used to absorb and transmit heat to the cooler areas adjacent thereto, while the light-colored panels with low emissivity are used to reflect heat back towards its source. The object of the black panels is to lower the clock motor tempera ture located in switch compartment and the solenoid and 1- hour timer motor temperatures located in the back air passage. This is to use standard parts. Higher temperature resistance coil and solenoid insulation could be used to solve the problem in an alternate way.

It will be appreciated that with certain design requirements to be met, and with limits on costs, the provision of each of the described features contributes toward the oven as a whole meeting the established requirements as to temperatures and cost. It will also be appreciated that if certain cost limitations are omitted some of the features described may be found to be unnecessary.

Finally, it is considered surprising that for an oven adapted to run at relatively high temperatures, a structural arrangement according to the invention can be provided which meets the established temperature requirements where the airflow for cooling and limiting the external surfaces of the oven is provided solely by free convection. This is in contrast to the air inducing means apparently required for the version of the lower temperature self-cleaning oven described in US. Pat. No. 3,310,046 noted before. It is believed that the provision of the air passages (including a rear air passage) in open communication with each other, the isolation thermally and from an airflow standpoint of the control and wiring chamber from the air passages, the provision of the relatively lengthy vent duct in the top air passage, and with the exhaust duct being in good heat conducting relation to the lower wall of the top air passage, all contribute substantially to the performance of the cooling system according to the invention. A distinct advantage provided by the use of a free convection cooling system is that the omission of a fan also results in the omission of any bafiles or restricted area openings in which the fan operates, so that there is no problem of fan failure and blockage by fans and baffles if there is a fan failure. Of course, the omission of any fan or blower means or air-inducing means also avoids any problems of control of the fan and the integration of that control into the remainder of the control system. Also, the provision of a free convection system results in a convection airflow generally proportional to its need since the maximum convection airflow occurs when the emission of heat from the oven is the greatest.

We claim as our invention:

1. A built-in wall oven of the pyrolytic self-cleaning type including:

an oven liner forming an oven cavity having an open front;

a door for closing said open front;

thermal insulation surrounding said liner on the top, bottom, rear and opposite sides thereof; wall means spaced outwardly from said insulation along at least the top, rear and opposite ones of said sides to define airflow passages in open communication with each other;

means defining an air inlet across substantially the entire front width of said oven and at a location below said oven to admit room air to said passages;

a control and wiring chamber overlying said top air passage and having a control panel forming the front wall of said chamber;

an air outlet opening for said passages at the front of said air passage, said air outlet opening being located between said control panel and the top portion of said door;

an oven exhaust gas duct having an inlet communicating with said oven cavity and extending for at least half the depth of the oven in said top air passage to place said duct in open heat transfer relation with the air passing through said top air passage, said duct having a discharge opening between said top of said door and said control panel;

a metallic panel overlying said thermal insulation on the top of said oven cavity and forming the bottom wall of said top air passage;

means securing said exhaust duct to said metallic panel in relatively good heat conducting relation to promote the transfer of heat from said exhaust duct to said metallic panel;

thermal insulation overlying said wall means forming the top wall of said top passage to thermally insulate said control chamber from said top passage; and

said airflow passages being devoid of air flow inducing means therein whereby the airflow through said passages results from free convection of room air in accordance with the emission of heat from said oven.

2. An oven according to claim 1 wherein:

the rear edge of said top passage wall means terminates short of said rear wall means to provide a gap therebetween; and

said thermal insulation overlying said top wall of said top passage extends to said rear wall means to provide a flexible seal through which wiring can pass through said gap.

3. A built-in wall oven of the pyrolytic self-cleaning type including:

an oven liner forming an oven cavity having an open front;

a door for closing said open front;

thermal insulation surrounding said liner on the top, bottom, rear and opposite sides thereof;

wall means space outwardly from said insulation along at least the top, rear and opposite ones of said sides to define airflow passages in open communication with each other;

means defining an air inlet across substantially the entire front width of said oven and at a location below said oven to admit room air to said passages;

a control and wiring chamber overlying said top air passage and having a control panel forming the front wall of said chamber;

an air outlet opening for said passages at the front of said air passage, said air outlet opening being located between said control panel and the top portion of said door;

an oven exhaust gas duct having an inlet communicating with said oven cavity and extending for at least half the depth of the oven in said top air passage to place said duct in open heat transfer relation with the air passing through said top air passage, said duct having a discharge opening between said top of said door and said control panel;

a top wall for said control chamber having a relatively high emissivity for promoting the absorption and radiation of heat from said top wall;

said wall means forming the outer walls of said side passages are of a relatively low emissivity for promoting the reflection of heat back towards said oven; and

said airflow passages being devoid of airflow inducing means therein whereby the airflow through said passages resulting from free convection of room air in accordance with the emission of heat from said oven. 

1. A built-in wall oven of the pyrolytic self-cleaning type including: an oven liner forming an oven cavity having an open front; a door for closing said open front; thermal insulation surrounding said liner on the top, bottom, rear and opposite sides thereof; wall means spaced outwardly from said insulation along at least the top, rear and opposite ones of said sides to define airflow passages in open communication with each other; means defining an air inlet across substantially the entire front width of said oven and at a location below said oven to admit room air to said passages; a control and wiring chamber overlying said top air passage and having a control panel forming the front wall of said chamber; an air outlet opening for said passages at the front of said air passage, said air outlet opening being located between said control panel and the top portion of said door; an oven exhaust gas duct having an inlet communicating with said oven cavity and extending for at least half the depth of the oven in said top air passage to place said duct in open heat transfer relation with the air passing through said top air passage, said duct having a discharge opening between said top of said door and said control panel; a metallic panel overlying said thermal insulation on the top of said oven cavity and forming the bottom wall of said top air passage; means securing said exhaust duct to said metallic panel in relatively good heat conducting relation to promote the transfer of heat from said exhaust duct to said metallic panel; thermal insulation overlying said wall means forming the top wall of said top passage to thermally insulate said control chamber from said top passage; and said airflow passages being devoid of air flow inducing means therein whereby the airflow through said passages results from free convection of room air in accordance with the emission of heat from said oven.
 2. An oven according to claim 1 wherein: the rear edge of said top passage wall means terminates short of said rear wall means to provide a gap therebetween; and said thermal insulation overlying said top wall of said top passage extends to said rear wall means to provide a flexible seal through which wiring can pass through said gap.
 3. A built-in wall oven of the pyrolytic self-cleaning type including: an oven liner forming an oven cavity having an open front; a door for closing said open front; thermal insulation surrounding said liner on the top, bottom, rear and opposite sides thereof; wall means space outwardly from said insulation along at least the top, rear and opposite ones of said sides to define airflow passages in open communication with each other; means defining an air inlet across substantially the entire front width of said oven and at a location below said oven to admit room air to said passages; a control and wiring chamber overlying said top air passage and having a control panel forming the front wall of said chamber; an air outlet opening for said passages at the front of said air passage, said air outlet opening being located between said conTrol panel and the top portion of said door; an oven exhaust gas duct having an inlet communicating with said oven cavity and extending for at least half the depth of the oven in said top air passage to place said duct in open heat transfer relation with the air passing through said top air passage, said duct having a discharge opening between said top of said door and said control panel; a top wall for said control chamber having a relatively high emissivity for promoting the absorption and radiation of heat from said top wall; said wall means forming the outer walls of said side passages are of a relatively low emissivity for promoting the reflection of heat back towards said oven; and said airflow passages being devoid of airflow inducing means therein whereby the airflow through said passages resulting from free convection of room air in accordance with the emission of heat from said oven. 